A packing made of a film or sheet which is well suited for a real sealing welding, e.g., along the sides, is difficult to tear-up weld or "peel seal weld", so that the weld is peelable in a reasonably well defined manner. This problem has been overcome in the past by forming the film or sheet in the entire packing of a so-called "peel seal" material. Strips of closing profiled portions made of a conventional packing material, that is a non peel seal material, have been welded to opposed surfaces of such peel seal material packings to enable them to be closed and reclosed. However, these known packings have been problematical in that during opening, peeling can extend beyond the mouth opening into the sides of the packing and/or the strips with the profiled portions can separate from the sheet material of the packing.
The requirement for selecting a peel seal material for the packing material also restricts the freedom of the user in choosing the material for the packing. For example, a non peel seal material may be more desirable from the standpoint of obtaining higher integrity packings, i.e., fewer leakers or defective seals, in packings made with high speed machines. Peel seal materials are also more expensive than conventional materials.